Farm Table says:
Evaluation of Columbia, USMARC-Composite, Suffolk, and Texel rams as terminal sires in an extensive rangeland production system
The primary terminal sire in the United States is the Suffolk, favoured for its favourable growth rate and leanness. To date, Suffolk research has focussed on the favourable growth and leanness, however producers have criticised the fitness of lambs sired by Suffolks.
The objective of this study was to estimate breed-of-ram effects on ewe fertility, prolificacy, and dystocia, as well as the sire breed effects on lamb survival and growth until weaning.
It looked at evaluating the following terminal sire breeds joined to an adult Rambouillet ewes in an extensive rangeland productions system:
- USMARC-Composite (50% Columbia, 25% Hampshire, 25% Suffolk)
This was a three-year study with the progeny of approximately 22 grams of each breed tested. Ewes were selected each year from 700 available ewes, based on age and average annual body weight of lambs weaned. Ewes were single-sided.
The research found that ram breed did not:
- Affect ewe fertility
- Total number born per ewe lambing
- Number born alive per ewe lambing
- Number weaned per ewe lambing
However, dystocia rates were different for ewes mated to different breeds. The results were:
- Columbia – 12.2%
- Composite – 13.5%
- Suffolk – 25.7%
- Texel – 31.9%
However, these results were based on one year of data and the differences were not repeated in the second year.
Other results included:
- Suffolk-sired lambs were heavier at birth (5.5kg) and weaning (40.3kg)
The researchers concluded that the use of Suffolk rams is “warranted to improved preweaning growth of market lambs and is not predicted to affect ewe fertility, ewe prolificacy, dystocia, or lamb survival compared with the other sire breeds we tested”.